激素对蚊虫免疫系统调控的分子机制

Aedes mosquitoes transmit devastating flavivirus, such as Dengue virus, West Nile virus, Zika virus, and several other viruses which might cause encephalitis. Anautogenous mosquitoes need vertebrate blood for their egg maturation, which makes them vectors of devastating human diseases. The fat body is the insect tissue responsible for metabolism, immunity, and reproduction. Juvenile hormone (JH) and 20-hydroxyecdysone (20E) regulates post-eclosion (PE) and post blood meal (PBM) fat body development respectively. The gene expression dynamics in mosquito Aedes aegypti during reproductive cycle has been characterized recently, founding the basis for investigating hormone regulated immunity. We have also shown that major components of immune pathway genes were induced in response to the microbial infection. Here, immune gene regulated by JH and 20E will be revealed firstly by analysis of transcriptome. We will perform fat body transcriptome with EcR, the 20E receptor, silenced. Differential expressed gene repertoire will be analyzed as well as the implication of Toll pathway and melanization genes in the anti-fungi immunity will be revealed. We will also analyze pervious Met depleted fat body transcriptome of A. aegypti to select immune genes regulated by Met, the JH receptor. Furthermore, it will be tested whether mosquito with the impaired JH or 20E signaling by RNA interference-mediated depletion of Met or EcR will have an increased survival rate after the infection of an entomopathogenic fungus or bacterium. The direct regulation of immune genes by Met or EcR will be evaluated by cell culture, electrophoretic mobility shift assay (EMSA), and luciferase assay. These experiments will suggest a key role of hormone in the regulation of mosquito immunity against microbial infection. This acquired knowledge will be extremely valuable toward future strategies to control mosquito borne diseases.

埃及伊蚊是登革热、寨卡等重要的虫媒病毒的传播媒介。由于蚊虫在其生活周期中需要反复吸血，这使其成为多种传染病的媒介。蚊虫生殖循环过程是由保幼激素和蜕皮激素共同调控的。研究激素对蚊虫抵御病原体免疫应答的调节机制具有重要的理论意义和实用价值。本研究着眼于揭示激素对蚊虫免疫体统的调节机制。首先利用高通量转录组测序和生物信息学方法，分析保幼激素和蜕皮激素对埃及伊蚊免疫基因的表达调节作用；然后利用RNA干扰沉默，结合实时定量PCR等分析激素调节伊蚊对真菌和革兰氏阴性菌等病原体的免疫应答机制，探索激素对免疫信号通路调控；最后利用免疫印迹、电泳迁移率等方法分析蚊虫在真菌和细菌感染状态下，免疫基因受激素调控的差异表达情况，通过对蚊虫存活率分析，解析受激素调控的抗真菌免疫途径上的关键基因。通过本课题的研究，将从分子水平明确激素对蚊虫免疫系统的调节作用机制，为通过阻断传播病毒而防治虫媒病提供理论参考。

蚊虫是重要的虫媒疾病传播媒介。蚊虫生殖循环过程是由保幼激素（JH）和蜕皮激素（20E）共同调控的，由于产卵生殖营养的需要，蚊虫在其生活周期中需要反复吸血，这使其成为多种人类致病因子的传染媒介。研究激素对蚊虫抵御病原体免疫应答的调节机制具有重要的理论意义和实用价值。本研究以激素调控蚊虫免疫作为出发点，重点研究了激素在蚊虫抗病原免疫过程中的调控作用。在埃及伊蚊蜕皮后，JH通过其受体Met抑制了脂肪代谢相关酶和免疫相关基因的表达。进一步，抗菌肽Dpt的表达受到Met的直接调控。而20E主要通过其受体EcR调节蚊虫对细菌病原体的免疫应答反应。此外，通过转录组分析，我们还鉴定出多个参与激素调节蚊虫免疫的关键基因。通过本课题的研究，明确激素在蚊虫免疫系统的调节作用机制，从分子水平上进一步明确激素在调节昆虫免疫系统中的作用，为蚊虫防治提供理论参考，同时也为寻找新的生物杀虫剂提供新的思路。